In a display device using an organic EL element, a balance between a high luminous efficiency and a low outside light reflectivity needs to be achieved. While a circular polarizing plate may be provided on the emission side to reduce the outside light reflectivity to approximately zero in principle, its light extraction efficiency is reduced by less than half so that the high luminous efficiency is not obtained. This is because more than half of light emitted from the organic EL element is also absorbed by the circular polarizing plate.
Japanese Patent Application Laid-Open No. 2003-17264 (Patent Literature 1) discloses a display device including a plurality of light emitting sections by stacking a plurality of first electrodes in a line shape, an organic layer including a light emitting layer on the first electrodes, and a plurality of second electrodes in a line shape to intersect the first electrodes on the organic layer. A light absorption layer existing below the plurality of first electrodes in close contact therewith is arranged to prevent luminance from decreasing while suppressing outside light reflection.
Japanese Patent Application Laid-Open No. 2004-271963 (Patent Literature 2) discloses a display device including a light emitting element, a solar battery, in which an amorphous silicon substrate, a single crystalline silicon substrate, a roughened silicon substrate, and a light absorption layer such as a black insulating sheet are provided to contact the light emitting element to suppress outside light reflection.
Japanese Patent Application Laid-Open No. 2003-223993 (Patent Literature 3) discloses a display device in which an antireflection layer is provided below an organic EL element to prevent outside light reflection, and also discusses an example in which a circuit layer and an element substrate are arranged between the organic EL element and the antireflection layer.
Japanese Patent Application Laid-Open No. 2005-222724 (Patent Literature 4) discloses a display device including a light emitting element having an electrooptical layer between a pair of electrodes, in which one of the electrodes is formed on a surface of a light absorption layer and the light absorption layer is patterned to match a shape of the one electrode.
In the display devices disclosed in Patent Literatures 1 to 4, the outside light reflection caused by an electrode of the light emitting element can be significantly prevented because it is absorbed by the light absorption layer or the antireflection layer. However, half of light emitted within the organic EL element or a quantum dot light emitting element is absorbed by the light absorption layer or the antireflection layer, resulting in reduced luminous efficiency. Patent Literature 3 also discusses an example in which the circuit layer and the substrate are provided between the organic EL element and the antireflection layer. However, the circuit layer includes various types of wirings, a capacitive electrode, and a TFT (Thin Film Transistor). When the wirings, the capacitive element, and the TFT are illuminated with outside light, the outside light is reflected, leading a reduction in contrast. When the TFT is illuminated with outside light, this causes a malfunction in the TFT. If only the substrate is provided between the organic EL element and the antireflection layer, a region where the organic EL element is provided cannot be effectively utilized so that there is a problem in high refinement of the display device. Further, an interface between the substrate and a lower electrode of the organic EL element is rough. Display is feared to be adversely affected by reflection on the interface. This is because while the substrate is formed of glass, polyimide, or the like, roughness of its surface and a surface state by a foreign material or the like are not more strictly managed than those on layers above the circuit layer.